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                    Recover捕获异常
            
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                    方法
            
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                    基于指针对象的方法
            
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                    通过嵌入结构体来扩展类型
            
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                    方法值和方法表达式
            
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                    示例: Bit数组
            
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                    封装
            
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                    接口
            
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                    接口是合约
            
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                    接口类型
            
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                    实现接口的条件
            
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                    flag.Value接口
            
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                    接口值
            
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                    sort.Interface接口
            
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                    http.Handler接口
            
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                    error接口
            
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                    示例: 表达式求值
            
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                    类型断言
            
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                    基于类型断言识别错误类型
            
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                    通过类型断言查询接口
            
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                    类型分支
            
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                    示例: 基于标记的XML解码
            
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                    补充几点
            
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                    Goroutines和Channels
            
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                    Goroutines
            
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                    示例: 并发的Clock服务
            
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                    示例: 并发的Echo服务
            
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                    Channels
            
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                    并发的循环
            
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        <li class="chapter " data-level="1.9.6" data-path="../ch8/ch8-06.html">
            
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                    示例: 并发的Web爬虫
            
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        <li class="chapter " data-level="1.9.7" data-path="../ch8/ch8-07.html">
            
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                    基于select的多路复用
            
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                    示例: 并发的目录遍历
            
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                    并发的退出
            
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                    示例: 聊天服务
            
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        <li class="chapter " data-level="1.10" data-path="../ch9/ch9.html">
            
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                    基于共享变量的并发
            
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                    竞争条件
            
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                    sync.Mutex互斥锁
            
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        <li class="chapter " data-level="1.10.3" data-path="../ch9/ch9-03.html">
            
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                    sync.RWMutex读写锁
            
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                    内存同步
            
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                    sync.Once惰性初始化
            
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        <li class="chapter " data-level="1.10.6" data-path="../ch9/ch9-06.html">
            
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                    竞争条件检测
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.10.7" data-path="../ch9/ch9-07.html">
            
                <a href="../ch9/ch9-07.html">
            
                    
                    示例: 并发的非阻塞缓存
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.10.8" data-path="../ch9/ch9-08.html">
            
                <a href="../ch9/ch9-08.html">
            
                    
                    Goroutines和线程
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.11" data-path="../ch10/ch10.html">
            
                <a href="../ch10/ch10.html">
            
                    
                    包和工具
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.11.1" data-path="../ch10/ch10-01.html">
            
                <a href="../ch10/ch10-01.html">
            
                    
                    包简介
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.2" data-path="../ch10/ch10-02.html">
            
                <a href="../ch10/ch10-02.html">
            
                    
                    导入路径
            
                </a>
            

            
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        <li class="chapter " data-level="1.11.3" data-path="../ch10/ch10-03.html">
            
                <a href="../ch10/ch10-03.html">
            
                    
                    包声明
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.4" data-path="../ch10/ch10-04.html">
            
                <a href="../ch10/ch10-04.html">
            
                    
                    导入声明
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.5" data-path="../ch10/ch10-05.html">
            
                <a href="../ch10/ch10-05.html">
            
                    
                    包的匿名导入
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.6" data-path="../ch10/ch10-06.html">
            
                <a href="../ch10/ch10-06.html">
            
                    
                    包和命名
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.7" data-path="../ch10/ch10-07.html">
            
                <a href="../ch10/ch10-07.html">
            
                    
                    工具
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.12" data-path="../ch11/ch11.html">
            
                <a href="../ch11/ch11.html">
            
                    
                    测试
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.12.1" data-path="../ch11/ch11-01.html">
            
                <a href="../ch11/ch11-01.html">
            
                    
                    go test
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.2" data-path="../ch11/ch11-02.html">
            
                <a href="../ch11/ch11-02.html">
            
                    
                    测试函数
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.3" data-path="../ch11/ch11-03.html">
            
                <a href="../ch11/ch11-03.html">
            
                    
                    测试覆盖率
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.4" data-path="../ch11/ch11-04.html">
            
                <a href="../ch11/ch11-04.html">
            
                    
                    基准测试
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.5" data-path="../ch11/ch11-05.html">
            
                <a href="../ch11/ch11-05.html">
            
                    
                    剖析
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.6" data-path="../ch11/ch11-06.html">
            
                <a href="../ch11/ch11-06.html">
            
                    
                    示例函数
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.13" data-path="../ch12/ch12.html">
            
                <a href="../ch12/ch12.html">
            
                    
                    反射
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.13.1" data-path="../ch12/ch12-01.html">
            
                <a href="../ch12/ch12-01.html">
            
                    
                    为何需要反射?
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.2" data-path="../ch12/ch12-02.html">
            
                <a href="../ch12/ch12-02.html">
            
                    
                    reflect.Type和reflect.Value
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.3" data-path="../ch12/ch12-03.html">
            
                <a href="../ch12/ch12-03.html">
            
                    
                    Display递归打印
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.4" data-path="../ch12/ch12-04.html">
            
                <a href="../ch12/ch12-04.html">
            
                    
                    示例: 编码S表达式
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.5" data-path="../ch12/ch12-05.html">
            
                <a href="../ch12/ch12-05.html">
            
                    
                    通过reflect.Value修改值
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.6" data-path="../ch12/ch12-06.html">
            
                <a href="../ch12/ch12-06.html">
            
                    
                    示例: 解码S表达式
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.7" data-path="../ch12/ch12-07.html">
            
                <a href="../ch12/ch12-07.html">
            
                    
                    获取结构体字段标签
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.8" data-path="../ch12/ch12-08.html">
            
                <a href="../ch12/ch12-08.html">
            
                    
                    显示一个类型的方法集
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.9" data-path="../ch12/ch12-09.html">
            
                <a href="../ch12/ch12-09.html">
            
                    
                    几点忠告
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.14" data-path="../ch13/ch13.html">
            
                <a href="../ch13/ch13.html">
            
                    
                    底层编程
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.14.1" data-path="../ch13/ch13-01.html">
            
                <a href="../ch13/ch13-01.html">
            
                    
                    unsafe.Sizeof, Alignof 和 Offsetof
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.2" data-path="../ch13/ch13-02.html">
            
                <a href="../ch13/ch13-02.html">
            
                    
                    unsafe.Pointer
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.3" data-path="../ch13/ch13-03.html">
            
                <a href="../ch13/ch13-03.html">
            
                    
                    示例: 深度相等判断
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.4" data-path="../ch13/ch13-04.html">
            
                <a href="../ch13/ch13-04.html">
            
                    
                    通过cgo调用C代码
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.5" data-path="../ch13/ch13-05.html">
            
                <a href="../ch13/ch13-05.html">
            
                    
                    几点忠告
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.15" data-path="../appendix/appendix.html">
            
                <a href="../appendix/appendix.html">
            
                    
                    附录
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.15.1" data-path="../appendix/appendix-a-errata.html">
            
                <a href="../appendix/appendix-a-errata.html">
            
                    
                    附录A：原文勘误
            
                </a>
            

            
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        <li class="chapter " data-level="1.15.2" data-path="../appendix/appendix-b-author.html">
            
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                    附录B：作者译者
            
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        <li class="chapter " data-level="1.15.3" data-path="../appendix/appendix-c-cpoyright.html">
            
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                    附录C：译文授权
            
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        <li class="chapter " data-level="1.15.4" data-path="../appendix/appendix-d-translations.html">
            
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                    附录D：其它语言
            
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                                <h2 id="24-&#x8D4B;&#x503C;">2.4. &#x8D4B;&#x503C;</h2>
<p>&#x4F7F;&#x7528;&#x8D4B;&#x503C;&#x8BED;&#x53E5;&#x53EF;&#x4EE5;&#x66F4;&#x65B0;&#x4E00;&#x4E2A;&#x53D8;&#x91CF;&#x7684;&#x503C;&#xFF0C;&#x6700;&#x7B80;&#x5355;&#x7684;&#x8D4B;&#x503C;&#x8BED;&#x53E5;&#x662F;&#x5C06;&#x8981;&#x88AB;&#x8D4B;&#x503C;&#x7684;&#x53D8;&#x91CF;&#x653E;&#x5728;=&#x7684;&#x5DE6;&#x8FB9;&#xFF0C;&#x65B0;&#x503C;&#x7684;&#x8868;&#x8FBE;&#x5F0F;&#x653E;&#x5728;=&#x7684;&#x53F3;&#x8FB9;&#x3002;</p>
<pre><code class="lang-Go">x = <span class="hljs-number">1</span>                       <span class="hljs-comment">// &#x547D;&#x540D;&#x53D8;&#x91CF;&#x7684;&#x8D4B;&#x503C;</span>
*p = <span class="hljs-literal">true</span>                   <span class="hljs-comment">// &#x901A;&#x8FC7;&#x6307;&#x9488;&#x95F4;&#x63A5;&#x8D4B;&#x503C;</span>
person.name = <span class="hljs-string">&quot;bob&quot;</span>         <span class="hljs-comment">// &#x7ED3;&#x6784;&#x4F53;&#x5B57;&#x6BB5;&#x8D4B;&#x503C;</span>
count[x] = count[x] * scale <span class="hljs-comment">// &#x6570;&#x7EC4;&#x3001;slice&#x6216;map&#x7684;&#x5143;&#x7D20;&#x8D4B;&#x503C;</span>
</code></pre>
<p>&#x7279;&#x5B9A;&#x7684;&#x4E8C;&#x5143;&#x7B97;&#x672F;&#x8FD0;&#x7B97;&#x7B26;&#x548C;&#x8D4B;&#x503C;&#x8BED;&#x53E5;&#x7684;&#x590D;&#x5408;&#x64CD;&#x4F5C;&#x6709;&#x4E00;&#x4E2A;&#x7B80;&#x6D01;&#x5F62;&#x5F0F;&#xFF0C;&#x4F8B;&#x5982;&#x4E0A;&#x9762;&#x6700;&#x540E;&#x7684;&#x8BED;&#x53E5;&#x53EF;&#x4EE5;&#x91CD;&#x5199;&#x4E3A;&#xFF1A;</p>
<pre><code class="lang-Go">count[x] *= scale
</code></pre>
<p>&#x8FD9;&#x6837;&#x53EF;&#x4EE5;&#x7701;&#x53BB;&#x5BF9;&#x53D8;&#x91CF;&#x8868;&#x8FBE;&#x5F0F;&#x7684;&#x91CD;&#x590D;&#x8BA1;&#x7B97;&#x3002;</p>
<p>&#x6570;&#x503C;&#x53D8;&#x91CF;&#x4E5F;&#x53EF;&#x4EE5;&#x652F;&#x6301;<code>++</code>&#x9012;&#x589E;&#x548C;<code>--</code>&#x9012;&#x51CF;&#x8BED;&#x53E5;&#xFF08;&#x8BD1;&#x6CE8;&#xFF1A;&#x81EA;&#x589E;&#x548C;&#x81EA;&#x51CF;&#x662F;&#x8BED;&#x53E5;&#xFF0C;&#x800C;&#x4E0D;&#x662F;&#x8868;&#x8FBE;&#x5F0F;&#xFF0C;&#x56E0;&#x6B64;<code>x = i++</code>&#x4E4B;&#x7C7B;&#x7684;&#x8868;&#x8FBE;&#x5F0F;&#x662F;&#x9519;&#x8BEF;&#x7684;&#xFF09;&#xFF1A;</p>
<pre><code class="lang-Go">v := <span class="hljs-number">1</span>
v++    <span class="hljs-comment">// &#x7B49;&#x4EF7;&#x65B9;&#x5F0F; v = v + 1&#xFF1B;v &#x53D8;&#x6210; 2</span>
v--    <span class="hljs-comment">// &#x7B49;&#x4EF7;&#x65B9;&#x5F0F; v = v - 1&#xFF1B;v &#x53D8;&#x6210; 1</span>
</code></pre>
<h3 id="241-&#x5143;&#x7EC4;&#x8D4B;&#x503C;">2.4.1. &#x5143;&#x7EC4;&#x8D4B;&#x503C;</h3>
<p>&#x5143;&#x7EC4;&#x8D4B;&#x503C;&#x662F;&#x53E6;&#x4E00;&#x79CD;&#x5F62;&#x5F0F;&#x7684;&#x8D4B;&#x503C;&#x8BED;&#x53E5;&#xFF0C;&#x5B83;&#x5141;&#x8BB8;&#x540C;&#x65F6;&#x66F4;&#x65B0;&#x591A;&#x4E2A;&#x53D8;&#x91CF;&#x7684;&#x503C;&#x3002;&#x5728;&#x8D4B;&#x503C;&#x4E4B;&#x524D;&#xFF0C;&#x8D4B;&#x503C;&#x8BED;&#x53E5;&#x53F3;&#x8FB9;&#x7684;&#x6240;&#x6709;&#x8868;&#x8FBE;&#x5F0F;&#x5C06;&#x4F1A;&#x5148;&#x8FDB;&#x884C;&#x6C42;&#x503C;&#xFF0C;&#x7136;&#x540E;&#x518D;&#x7EDF;&#x4E00;&#x66F4;&#x65B0;&#x5DE6;&#x8FB9;&#x5BF9;&#x5E94;&#x53D8;&#x91CF;&#x7684;&#x503C;&#x3002;&#x8FD9;&#x5BF9;&#x4E8E;&#x5904;&#x7406;&#x6709;&#x4E9B;&#x540C;&#x65F6;&#x51FA;&#x73B0;&#x5728;&#x5143;&#x7EC4;&#x8D4B;&#x503C;&#x8BED;&#x53E5;&#x5DE6;&#x53F3;&#x4E24;&#x8FB9;&#x7684;&#x53D8;&#x91CF;&#x5F88;&#x6709;&#x5E2E;&#x52A9;&#xFF0C;&#x4F8B;&#x5982;&#x6211;&#x4EEC;&#x53EF;&#x4EE5;&#x8FD9;&#x6837;&#x4EA4;&#x6362;&#x4E24;&#x4E2A;&#x53D8;&#x91CF;&#x7684;&#x503C;&#xFF1A;</p>
<pre><code class="lang-Go">x, y = y, x

a[i], a[j] = a[j], a[i]
</code></pre>
<p>&#x6216;&#x8005;&#x662F;&#x8BA1;&#x7B97;&#x4E24;&#x4E2A;&#x6574;&#x6570;&#x503C;&#x7684;&#x7684;&#x6700;&#x5927;&#x516C;&#x7EA6;&#x6570;&#xFF08;GCD&#xFF09;&#xFF08;&#x8BD1;&#x6CE8;&#xFF1A;GCD&#x4E0D;&#x662F;&#x90A3;&#x4E2A;&#x654F;&#x611F;&#x5B57;&#xFF0C;&#x800C;&#x662F;greatest common divisor&#x7684;&#x7F29;&#x5199;&#xFF0C;&#x6B27;&#x51E0;&#x91CC;&#x5FB7;&#x7684;GCD&#x662F;&#x6700;&#x65E9;&#x7684;&#x975E;&#x5E73;&#x51E1;&#x7B97;&#x6CD5;&#xFF09;&#xFF1A;</p>
<pre><code class="lang-Go"><span class="hljs-keyword">func</span> gcd(x, y <span class="hljs-keyword">int</span>) <span class="hljs-keyword">int</span> {
    <span class="hljs-keyword">for</span> y != <span class="hljs-number">0</span> {
        x, y = y, x%y
    }
    <span class="hljs-keyword">return</span> x
}
</code></pre>
<p>&#x6216;&#x8005;&#x662F;&#x8BA1;&#x7B97;&#x6590;&#x6CE2;&#x7EB3;&#x5951;&#x6570;&#x5217;&#xFF08;Fibonacci&#xFF09;&#x7684;&#x7B2C;N&#x4E2A;&#x6570;&#xFF1A;</p>
<pre><code class="lang-Go"><span class="hljs-keyword">func</span> fib(n <span class="hljs-keyword">int</span>) <span class="hljs-keyword">int</span> {
    x, y := <span class="hljs-number">0</span>, <span class="hljs-number">1</span>
    <span class="hljs-keyword">for</span> i := <span class="hljs-number">0</span>; i &lt; n; i++ {
        x, y = y, x+y
    }
    <span class="hljs-keyword">return</span> x
}
</code></pre>
<p>&#x5143;&#x7EC4;&#x8D4B;&#x503C;&#x4E5F;&#x53EF;&#x4EE5;&#x4F7F;&#x4E00;&#x7CFB;&#x5217;&#x7410;&#x788E;&#x8D4B;&#x503C;&#x66F4;&#x52A0;&#x7D27;&#x51D1;&#xFF08;&#x8BD1;&#x6CE8;: &#x7279;&#x522B;&#x662F;&#x5728;for&#x5FAA;&#x73AF;&#x7684;&#x521D;&#x59CB;&#x5316;&#x90E8;&#x5206;&#xFF09;&#xFF0C;</p>
<pre><code class="lang-Go">i, j, k = <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">5</span>
</code></pre>
<p>&#x4F46;&#x5982;&#x679C;&#x8868;&#x8FBE;&#x5F0F;&#x592A;&#x590D;&#x6742;&#x7684;&#x8BDD;&#xFF0C;&#x5E94;&#x8BE5;&#x5C3D;&#x91CF;&#x907F;&#x514D;&#x8FC7;&#x5EA6;&#x4F7F;&#x7528;&#x5143;&#x7EC4;&#x8D4B;&#x503C;&#xFF1B;&#x56E0;&#x4E3A;&#x6BCF;&#x4E2A;&#x53D8;&#x91CF;&#x5355;&#x72EC;&#x8D4B;&#x503C;&#x8BED;&#x53E5;&#x7684;&#x5199;&#x6CD5;&#x53EF;&#x8BFB;&#x6027;&#x4F1A;&#x66F4;&#x597D;&#x3002;</p>
<p>&#x6709;&#x4E9B;&#x8868;&#x8FBE;&#x5F0F;&#x4F1A;&#x4EA7;&#x751F;&#x591A;&#x4E2A;&#x503C;&#xFF0C;&#x6BD4;&#x5982;&#x8C03;&#x7528;&#x4E00;&#x4E2A;&#x6709;&#x591A;&#x4E2A;&#x8FD4;&#x56DE;&#x503C;&#x7684;&#x51FD;&#x6570;&#x3002;&#x5F53;&#x8FD9;&#x6837;&#x4E00;&#x4E2A;&#x51FD;&#x6570;&#x8C03;&#x7528;&#x51FA;&#x73B0;&#x5728;&#x5143;&#x7EC4;&#x8D4B;&#x503C;&#x53F3;&#x8FB9;&#x7684;&#x8868;&#x8FBE;&#x5F0F;&#x4E2D;&#x65F6;&#xFF08;&#x8BD1;&#x6CE8;&#xFF1A;&#x53F3;&#x8FB9;&#x4E0D;&#x80FD;&#x518D;&#x6709;&#x5176;&#x5B83;&#x8868;&#x8FBE;&#x5F0F;&#xFF09;&#xFF0C;&#x5DE6;&#x8FB9;&#x53D8;&#x91CF;&#x7684;&#x6570;&#x76EE;&#x5FC5;&#x987B;&#x548C;&#x53F3;&#x8FB9;&#x4E00;&#x81F4;&#x3002;</p>
<pre><code class="lang-Go">f, err = os.Open(<span class="hljs-string">&quot;foo.txt&quot;</span>) <span class="hljs-comment">// function call returns two values</span>
</code></pre>
<p>&#x901A;&#x5E38;&#xFF0C;&#x8FD9;&#x7C7B;&#x51FD;&#x6570;&#x4F1A;&#x7528;&#x989D;&#x5916;&#x7684;&#x8FD4;&#x56DE;&#x503C;&#x6765;&#x8868;&#x8FBE;&#x67D0;&#x79CD;&#x9519;&#x8BEF;&#x7C7B;&#x578B;&#xFF0C;&#x4F8B;&#x5982;os.Open&#x662F;&#x7528;&#x989D;&#x5916;&#x7684;&#x8FD4;&#x56DE;&#x503C;&#x8FD4;&#x56DE;&#x4E00;&#x4E2A;error&#x7C7B;&#x578B;&#x7684;&#x9519;&#x8BEF;&#xFF0C;&#x8FD8;&#x6709;&#x4E00;&#x4E9B;&#x662F;&#x7528;&#x6765;&#x8FD4;&#x56DE;&#x5E03;&#x5C14;&#x503C;&#xFF0C;&#x901A;&#x5E38;&#x88AB;&#x79F0;&#x4E3A;ok&#x3002;&#x5728;&#x7A0D;&#x540E;&#x6211;&#x4EEC;&#x5C06;&#x770B;&#x5230;&#x7684;&#x4E09;&#x4E2A;&#x64CD;&#x4F5C;&#x90FD;&#x662F;&#x7C7B;&#x4F3C;&#x7684;&#x7528;&#x6CD5;&#x3002;&#x5982;&#x679C;map&#x67E5;&#x627E;&#xFF08;&#xA7;4.3&#xFF09;&#x3001;&#x7C7B;&#x578B;&#x65AD;&#x8A00;&#xFF08;&#xA7;7.10&#xFF09;&#x6216;&#x901A;&#x9053;&#x63A5;&#x6536;&#xFF08;&#xA7;8.4.2&#xFF09;&#x51FA;&#x73B0;&#x5728;&#x8D4B;&#x503C;&#x8BED;&#x53E5;&#x7684;&#x53F3;&#x8FB9;&#xFF0C;&#x5B83;&#x4EEC;&#x90FD;&#x53EF;&#x80FD;&#x4F1A;&#x4EA7;&#x751F;&#x4E24;&#x4E2A;&#x7ED3;&#x679C;&#xFF0C;&#x6709;&#x4E00;&#x4E2A;&#x989D;&#x5916;&#x7684;&#x5E03;&#x5C14;&#x7ED3;&#x679C;&#x8868;&#x793A;&#x64CD;&#x4F5C;&#x662F;&#x5426;&#x6210;&#x529F;&#xFF1A;</p>
<pre><code class="lang-Go">v, ok = m[key]             <span class="hljs-comment">// map lookup</span>
v, ok = x.(T)              <span class="hljs-comment">// type assertion</span>
v, ok = &lt;-ch               <span class="hljs-comment">// channel receive</span>
</code></pre>
<p>&#x8BD1;&#x6CE8;&#xFF1A;map&#x67E5;&#x627E;&#xFF08;&#xA7;4.3&#xFF09;&#x3001;&#x7C7B;&#x578B;&#x65AD;&#x8A00;&#xFF08;&#xA7;7.10&#xFF09;&#x6216;&#x901A;&#x9053;&#x63A5;&#x6536;&#xFF08;&#xA7;8.4.2&#xFF09;&#x51FA;&#x73B0;&#x5728;&#x8D4B;&#x503C;&#x8BED;&#x53E5;&#x7684;&#x53F3;&#x8FB9;&#x65F6;&#xFF0C;&#x5E76;&#x4E0D;&#x4E00;&#x5B9A;&#x662F;&#x4EA7;&#x751F;&#x4E24;&#x4E2A;&#x7ED3;&#x679C;&#xFF0C;&#x4E5F;&#x53EF;&#x80FD;&#x53EA;&#x4EA7;&#x751F;&#x4E00;&#x4E2A;&#x7ED3;&#x679C;&#x3002;&#x5BF9;&#x4E8E;&#x53EA;&#x4EA7;&#x751F;&#x4E00;&#x4E2A;&#x7ED3;&#x679C;&#x7684;&#x60C5;&#x5F62;&#xFF0C;map&#x67E5;&#x627E;&#x5931;&#x8D25;&#x65F6;&#x4F1A;&#x8FD4;&#x56DE;&#x96F6;&#x503C;&#xFF0C;&#x7C7B;&#x578B;&#x65AD;&#x8A00;&#x5931;&#x8D25;&#x65F6;&#x4F1A;&#x53D1;&#x751F;&#x8FD0;&#x884C;&#x65F6;panic&#x5F02;&#x5E38;&#xFF0C;&#x901A;&#x9053;&#x63A5;&#x6536;&#x5931;&#x8D25;&#x65F6;&#x4F1A;&#x8FD4;&#x56DE;&#x96F6;&#x503C;&#xFF08;&#x963B;&#x585E;&#x4E0D;&#x7B97;&#x662F;&#x5931;&#x8D25;&#xFF09;&#x3002;&#x4F8B;&#x5982;&#x4E0B;&#x9762;&#x7684;&#x4F8B;&#x5B50;&#xFF1A;</p>
<pre><code class="lang-Go">v = m[key]                <span class="hljs-comment">// map&#x67E5;&#x627E;&#xFF0C;&#x5931;&#x8D25;&#x65F6;&#x8FD4;&#x56DE;&#x96F6;&#x503C;</span>
v = x.(T)                 <span class="hljs-comment">// type&#x65AD;&#x8A00;&#xFF0C;&#x5931;&#x8D25;&#x65F6;panic&#x5F02;&#x5E38;</span>
v = &lt;-ch                  <span class="hljs-comment">// &#x7BA1;&#x9053;&#x63A5;&#x6536;&#xFF0C;&#x5931;&#x8D25;&#x65F6;&#x8FD4;&#x56DE;&#x96F6;&#x503C;&#xFF08;&#x963B;&#x585E;&#x4E0D;&#x7B97;&#x662F;&#x5931;&#x8D25;&#xFF09;</span>

_, ok = m[key]            <span class="hljs-comment">// map&#x8FD4;&#x56DE;2&#x4E2A;&#x503C;</span>
_, ok = mm[<span class="hljs-string">&quot;&quot;</span>], <span class="hljs-literal">false</span>     <span class="hljs-comment">// map&#x8FD4;&#x56DE;1&#x4E2A;&#x503C;</span>
_ = mm[<span class="hljs-string">&quot;&quot;</span>]                <span class="hljs-comment">// map&#x8FD4;&#x56DE;1&#x4E2A;&#x503C;</span>
</code></pre>
<p>&#x548C;&#x53D8;&#x91CF;&#x58F0;&#x660E;&#x4E00;&#x6837;&#xFF0C;&#x6211;&#x4EEC;&#x53EF;&#x4EE5;&#x7528;&#x4E0B;&#x5212;&#x7EBF;&#x7A7A;&#x767D;&#x6807;&#x8BC6;&#x7B26;<code>_</code>&#x6765;&#x4E22;&#x5F03;&#x4E0D;&#x9700;&#x8981;&#x7684;&#x503C;&#x3002;</p>
<pre><code class="lang-Go">_, err = io.Copy(dst, src) <span class="hljs-comment">// &#x4E22;&#x5F03;&#x5B57;&#x8282;&#x6570;</span>
_, ok = x.(T)              <span class="hljs-comment">// &#x53EA;&#x68C0;&#x6D4B;&#x7C7B;&#x578B;&#xFF0C;&#x5FFD;&#x7565;&#x5177;&#x4F53;&#x503C;</span>
</code></pre>
<h3 id="242-&#x53EF;&#x8D4B;&#x503C;&#x6027;">2.4.2. &#x53EF;&#x8D4B;&#x503C;&#x6027;</h3>
<p>&#x8D4B;&#x503C;&#x8BED;&#x53E5;&#x662F;&#x663E;&#x5F0F;&#x7684;&#x8D4B;&#x503C;&#x5F62;&#x5F0F;&#xFF0C;&#x4F46;&#x662F;&#x7A0B;&#x5E8F;&#x4E2D;&#x8FD8;&#x6709;&#x5F88;&#x591A;&#x5730;&#x65B9;&#x4F1A;&#x53D1;&#x751F;&#x9690;&#x5F0F;&#x7684;&#x8D4B;&#x503C;&#x884C;&#x4E3A;&#xFF1A;&#x51FD;&#x6570;&#x8C03;&#x7528;&#x4F1A;&#x9690;&#x5F0F;&#x5730;&#x5C06;&#x8C03;&#x7528;&#x53C2;&#x6570;&#x7684;&#x503C;&#x8D4B;&#x503C;&#x7ED9;&#x51FD;&#x6570;&#x7684;&#x53C2;&#x6570;&#x53D8;&#x91CF;&#xFF0C;&#x4E00;&#x4E2A;&#x8FD4;&#x56DE;&#x8BED;&#x53E5;&#x4F1A;&#x9690;&#x5F0F;&#x5730;&#x5C06;&#x8FD4;&#x56DE;&#x64CD;&#x4F5C;&#x7684;&#x503C;&#x8D4B;&#x503C;&#x7ED9;&#x7ED3;&#x679C;&#x53D8;&#x91CF;&#xFF0C;&#x4E00;&#x4E2A;&#x590D;&#x5408;&#x7C7B;&#x578B;&#x7684;&#x5B57;&#x9762;&#x91CF;&#xFF08;&#xA7;4.2&#xFF09;&#x4E5F;&#x4F1A;&#x4EA7;&#x751F;&#x8D4B;&#x503C;&#x884C;&#x4E3A;&#x3002;&#x4F8B;&#x5982;&#x4E0B;&#x9762;&#x7684;&#x8BED;&#x53E5;&#xFF1A;</p>
<pre><code class="lang-Go">medals := []<span class="hljs-keyword">string</span>{<span class="hljs-string">&quot;gold&quot;</span>, <span class="hljs-string">&quot;silver&quot;</span>, <span class="hljs-string">&quot;bronze&quot;</span>}
</code></pre>
<p>&#x9690;&#x5F0F;&#x5730;&#x5BF9;slice&#x7684;&#x6BCF;&#x4E2A;&#x5143;&#x7D20;&#x8FDB;&#x884C;&#x8D4B;&#x503C;&#x64CD;&#x4F5C;&#xFF0C;&#x7C7B;&#x4F3C;&#x8FD9;&#x6837;&#x5199;&#x7684;&#x884C;&#x4E3A;&#xFF1A;</p>
<pre><code class="lang-Go">medals[<span class="hljs-number">0</span>] = <span class="hljs-string">&quot;gold&quot;</span>
medals[<span class="hljs-number">1</span>] = <span class="hljs-string">&quot;silver&quot;</span>
medals[<span class="hljs-number">2</span>] = <span class="hljs-string">&quot;bronze&quot;</span>
</code></pre>
<p>map&#x548C;chan&#x7684;&#x5143;&#x7D20;&#xFF0C;&#x867D;&#x7136;&#x4E0D;&#x662F;&#x666E;&#x901A;&#x7684;&#x53D8;&#x91CF;&#xFF0C;&#x4F46;&#x662F;&#x4E5F;&#x6709;&#x7C7B;&#x4F3C;&#x7684;&#x9690;&#x5F0F;&#x8D4B;&#x503C;&#x884C;&#x4E3A;&#x3002;</p>
<p>&#x4E0D;&#x7BA1;&#x662F;&#x9690;&#x5F0F;&#x8FD8;&#x662F;&#x663E;&#x5F0F;&#x5730;&#x8D4B;&#x503C;&#xFF0C;&#x5728;&#x8D4B;&#x503C;&#x8BED;&#x53E5;&#x5DE6;&#x8FB9;&#x7684;&#x53D8;&#x91CF;&#x548C;&#x53F3;&#x8FB9;&#x6700;&#x7EC8;&#x7684;&#x6C42;&#x5230;&#x7684;&#x503C;&#x5FC5;&#x987B;&#x6709;&#x76F8;&#x540C;&#x7684;&#x6570;&#x636E;&#x7C7B;&#x578B;&#x3002;&#x66F4;&#x76F4;&#x767D;&#x5730;&#x8BF4;&#xFF0C;&#x53EA;&#x6709;&#x53F3;&#x8FB9;&#x7684;&#x503C;&#x5BF9;&#x4E8E;&#x5DE6;&#x8FB9;&#x7684;&#x53D8;&#x91CF;&#x662F;&#x53EF;&#x8D4B;&#x503C;&#x7684;&#xFF0C;&#x8D4B;&#x503C;&#x8BED;&#x53E5;&#x624D;&#x662F;&#x5141;&#x8BB8;&#x7684;&#x3002;</p>
<p>&#x53EF;&#x8D4B;&#x503C;&#x6027;&#x7684;&#x89C4;&#x5219;&#x5BF9;&#x4E8E;&#x4E0D;&#x540C;&#x7C7B;&#x578B;&#x6709;&#x7740;&#x4E0D;&#x540C;&#x8981;&#x6C42;&#xFF0C;&#x5BF9;&#x6BCF;&#x4E2A;&#x65B0;&#x7C7B;&#x578B;&#x7279;&#x6B8A;&#x7684;&#x5730;&#x65B9;&#x6211;&#x4EEC;&#x4F1A;&#x4E13;&#x95E8;&#x89E3;&#x91CA;&#x3002;&#x5BF9;&#x4E8E;&#x76EE;&#x524D;&#x6211;&#x4EEC;&#x5DF2;&#x7ECF;&#x8BA8;&#x8BBA;&#x8FC7;&#x7684;&#x7C7B;&#x578B;&#xFF0C;&#x5B83;&#x7684;&#x89C4;&#x5219;&#x662F;&#x7B80;&#x5355;&#x7684;&#xFF1A;&#x7C7B;&#x578B;&#x5FC5;&#x987B;&#x5B8C;&#x5168;&#x5339;&#x914D;&#xFF0C;nil&#x53EF;&#x4EE5;&#x8D4B;&#x503C;&#x7ED9;&#x4EFB;&#x4F55;&#x6307;&#x9488;&#x6216;&#x5F15;&#x7528;&#x7C7B;&#x578B;&#x7684;&#x53D8;&#x91CF;&#x3002;&#x5E38;&#x91CF;&#xFF08;&#xA7;3.6&#xFF09;&#x5219;&#x6709;&#x66F4;&#x7075;&#x6D3B;&#x7684;&#x8D4B;&#x503C;&#x89C4;&#x5219;&#xFF0C;&#x56E0;&#x4E3A;&#x8FD9;&#x6837;&#x53EF;&#x4EE5;&#x907F;&#x514D;&#x4E0D;&#x5FC5;&#x8981;&#x7684;&#x663E;&#x5F0F;&#x7684;&#x7C7B;&#x578B;&#x8F6C;&#x6362;&#x3002;</p>
<p>&#x5BF9;&#x4E8E;&#x4E24;&#x4E2A;&#x503C;&#x662F;&#x5426;&#x53EF;&#x4EE5;&#x7528;<code>==</code>&#x6216;<code>!=</code>&#x8FDB;&#x884C;&#x76F8;&#x7B49;&#x6BD4;&#x8F83;&#x7684;&#x80FD;&#x529B;&#x4E5F;&#x548C;&#x53EF;&#x8D4B;&#x503C;&#x80FD;&#x529B;&#x6709;&#x5173;&#x7CFB;&#xFF1A;&#x5BF9;&#x4E8E;&#x4EFB;&#x4F55;&#x7C7B;&#x578B;&#x7684;&#x503C;&#x7684;&#x76F8;&#x7B49;&#x6BD4;&#x8F83;&#xFF0C;&#x7B2C;&#x4E8C;&#x4E2A;&#x503C;&#x5FC5;&#x987B;&#x662F;&#x5BF9;&#x7B2C;&#x4E00;&#x4E2A;&#x503C;&#x7C7B;&#x578B;&#x5BF9;&#x5E94;&#x7684;&#x53D8;&#x91CF;&#x662F;&#x53EF;&#x8D4B;&#x503C;&#x7684;&#xFF0C;&#x53CD;&#x4E4B;&#x4EA6;&#x7136;&#x3002;&#x548C;&#x524D;&#x9762;&#x4E00;&#x6837;&#xFF0C;&#x6211;&#x4EEC;&#x4F1A;&#x5BF9;&#x6BCF;&#x4E2A;&#x65B0;&#x7C7B;&#x578B;&#x6BD4;&#x8F83;&#x7279;&#x6B8A;&#x7684;&#x5730;&#x65B9;&#x505A;&#x4E13;&#x95E8;&#x7684;&#x89E3;&#x91CA;&#x3002;</p>

                                
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